Abstract: An equation or state for pure associating fluids is developed by treating dipole-dipole interactions separately with perturbation theory and mean spherical approximation(MSA）,and treating hydrogen bond association with statistical associating fluid theory (SAFT）.The saturated vapor pressuresand liquid densities of 37 associating fluids（ater,alkanols,acids and amines)are correlated with molecular（or segment)microscopic parameters.It is shown that the corrdelated results with perturbatin theory are superior to mean spherical approximation and are consistent with the molecular simulation data.